Rotatable counterweight mechanism



June 23, 1959 a RI. GREIVELL 8 ROTATABLE COUNTERWEIGHT MECHANISM Filed D60. 5. 1956 2 Sheets-Sheet 1 INVENTOR. ROBERT L. Glaslwsu.

BY Y

ATTORNEYS R. L. GREIVELL ROTATABLE COUNTERWEIGHT MECHANISM June 23, 1959 2 Sheets-Sheet 2 Filed D60. 5, 1956 mmvrozz. 120552 T L. GEEIVELL TORNEYS United States Patent Ofiice 2,891,681 Patented June 23, 1959 2,891,681 ROTATABLE COUNTERWEIGHT MECHANISM Robert L. Greivell, Milwaukee, Wis., assignor to Caterpillar Tractor Co., Peoria, 111., a corporation of Cahfornia Application December 5, 1956, Serial No. 626,414 4 Claims. (Cl. 212-49) This invention relates to counterweight mechanisms for use on tractors which carry cranes or the like which extend outwardly from one side of the vehicle and require counter-balancing by a weight which may be extended from the opposite side.

It is common practice in many counterweight mechanisms to rigidly secure the weights on support arms pivotally connected at their lower ends to the vehicle with means for swinging the weight and arms as a unit in an are away from the vehicle. In such arrangements, maneuverability of the vehicle is limited because of the close proximity to the ground of the support arm in its fully extended position. Another problem encountered in the conventional counterweight mechanisms is the high hydraulic pressures required to move the weights the vertical distance from the fully extended to the fully retracted position. These high pressures are responsible for the abrupt operating action, generally associated with conventional counterweights, which decrease the life of the mechanism.

It is an object of the present invention to provide a counterweight mechanism having the weight portion rotatably secured to support arms .and stabilized by a pair of links relatively shorter than the support arms in a manner to swing the weight outwardly from the vehicle in a substantially horizontal plane which permits the use of relatively low hydraulic pressures and assures smoother operation.

Another object of the present invention is to provide a counterweight mechanism in which the desired outward travel of the weight portion is obtained by a relatively small amount of support arm movement, thereby permitting greater ground clearances.

Further and more specific objects and advantages of the invention will be made apparent in the following specification wherein reference is made to the accompanying drawings.

In the drawings:

Fig. 1 is a perspective view of a counterweight mechanism embodying the present invention on a track-type tractor and showing the weight in its fully extended position with parts broken away;

Fig. 2 is a transverse cross-sectional view the same counterweight mechanism in the fully retracted position taken generally along the line II--II in Fig. 1; and

Fig. 3 is a schematic development of the path described by the counterweight center of gravity.

In Fig. 1 of the drawings, the present invention is illustrated attached to a track-type vehicle generally shown at 8. The vehicle includes a conventional main frame 9 and truck frame 10. A mounting frame 11 is rigidly supported on the main and truck frames in a position to bridge the vehicle track as shown.

Support arms 12 are pivotally secured at their lower ends to frame 11 by a pair of pins, one of which is shown at 13. They are braced and connected to swing together by cross members 12a. A pair of stabilizer links 14, shorter in length than arms 12, are pivotally connected at their lower ends to frame 11 by pins 15. Furthermore, frame 11 pivotally supports the lower ends of a pair of hydraulic jacks 16 by pins indicated at 17.

A counterweight mass, indicated generally at 18, comprises preferably a plurality of heavy metal plates or laminations 19. Plates 19 are retained on a pair of spaced rail members 20 by through bolts 21. To reduce shearing forces, bolts 21 are positioned at the exact center of gravity of weights 19. A plurality of spaced brackets 22, integral with rails 20, retain pivot pins 23 upon which counterweight 18 is rotatably supported on the other ends of arms 12.

The space between pairs of brackets 22 is divided at one of their ends by a plate 24. Pins 25 extend through the brackets and plate 24 to provide a pivotal connection for the other end of links 14 and also provide a pivotal connection for the rod ends of jacks 16.

As best seen in Fig. 2, the counterweight 18 is normally carried in the retracted full line position. With weights 19 in this position, pivot pins 23 and 25 are located above the center of gravity 21 and spaced to each side of a line drawn vertically therethrough.

Upon retraction of jack 16 under hydraulic pressure, arm 12 and link 14 are rocked in a counterclockwise direction about their respective pivots 13 and 15. Link 14, being shorter in length than arm 12, swings through a smaller arc than does arm 12 thereby rotating weight 19 in a clockwise direction about pivot 23. As a result, weight 19 is moved in a substantially horizontal plane to the fully extended position indicated at 19'. With this arrangement, arm 12 moves through a much smaller are for substantially the same amount of counterweight travel provided by conventional mechanisms employing rigidly connected weights.

From the fully extended position, weights 19 are again drawn inwardly by a relatively small amount of hydraulic pressure acting to lengthen jacks 16. During this movement, the center of gravity 21 is required to be raised a minimum vertical distance from the point indicated at 21'.

Fig. 3 of the drawings discloses more clearly the path described by the counterweight center of gravity. In this figure straight solid lines are used to represent arm 12 and link 14. Lines 12 and 14 pivot about their ends at 13 and 15 to move through their respective arcs while pivots 23 and 25 associated with the other ends of lines 12 and 14 remain a constant distance from each other and from the center of gravity point 21. Line 14 being shorter than line 12 describes a shorter radius and thereby advances point 21 outward of points 23 and 25 to the fully extended position indicated by the points 23', 25' and 21'.

While the counterweight structure is disclosed herein in its application to a track-type vehicle, it is readily apparent that a similar counterweight may be used to advantage on other types of vehicles.

I claim:

1. A counter weight mechanism comprising a support structure, a support arm having an upper and a lower end portion, the lower end portion of said arm being pivotally connected to said support structure, a stabilizer link of shorter length than said support arm and having an upper and a lower end portion, the lower end portion of said stabilizer link being pivotally connected to said support structure, a weight member pivotally connected to the upper end portion of said arm and said stabilizer link, the points of pivotal connection between the upper ends of said arm and said weight member and said stabilizer link and said weight member being positioned above the center of gravity of said weight member and being spaced on opposite sides of a line drawn vertically through the center of gravity of the weight member while in retracted position, and hydraulic means for actuating said weight member outwardly of the support structure, whereby upon actuation of the mechanism outwardly of the support structure, the center of gravity of said weight member is shifted outwardly of the point of pivotal connection between said arm and said weight member and said weight member is tilted during outward movement.

2. A counterweight mechanism comprising a support structure, a support arm having an upper and lower end portion, the lower end portion of said arm being pivotally connected to said support structure, a stabilizer link of shorter length than said support arm and having an upper and a lower end portion, the lower end portion of said stabilizer link being pivotally connected to said structure, a weight member being pivotally connected to the upper end portion of said arm and said stabilizer link, the points of pivotal connection between the upper ends of said arm and said weight member and said stabilizer link and said weight member being positioned above the point of gravity of said weight member and being spaced on opposite sides of a line drawn Vertically through the center of gravity of said weight memher while in retracted position, and a hydraulic jack having upper and lower end portions, the lower end portion of said jack being pivotally connected to said support structure and the upper end portion of said jack being pivotally connected to said support structure such that the pivotal axis of the pivotal connection between the upper end portion of said jack and said weight member is substantially in alignment with the pivotal axis of the pivotal connection between the upper end portion of said stabilizer link and said weight member, whereby upon actuation of the mechanism outwardly of the support structure the center of gravity of said weight member is shifted outwardly of the point of pivotal connection between said arm and said weight member and said weight member is tilted during outward movement thereof.

3. A counter weight mechanism comprising a support structure, a weight member, and means connected between said support structure and said weight member for moving said weight member outwardly of said support structure, said last-mentioned means including a support arm having an upper and a lower end portion, the lower end portion of said arm being pivotally connected to said support structure, the upper end portion of said arm being pivotally connected to said member, a stabilizer link of shorter length than said arm and having an upper and lower end portion, the lower portion of said stabilizer link being pivotally connected to said support structure inwardly of the point of pivotal connection between said arm and said support structure, the upper end portion of said stabilizer link being pivotally connected to said weight member, a hydraulic jack having an upper end portion and a lower end portion, the lower end portion of said hydraulic jack being pivotally connected to said support structure outwardly of the pivotal connection between said stabilizer link and said support structure, the upper end portion of said hydraulic jack being pivotally connected to said weight member about a pivotal axis which is substantially in alignment with the pivotal axis of the pivotal connection between said stabilizer link and said weight member, the points of pivotal connection between said support arm and said weight member and said stabilizer link and said weight member being spaced above the center of gravity of said weight member and on opposite sides of a line drawn vertically through the center of gravity of the weight member while in retracted position, whereby upon actuation of the mechanism outwardly of the support structure the center of gravity of said weight member is shifted outwardly of the point of pivotal connection between said arm and said weight member and said weight member is tilted during outward movement thereof.

4. A counterweight mechanism as defined in claim 3, wherein the point of pivotal connection between said stabilizer link and said support structure is spaced a'substantial vertical distance above the point of pivotal interconnection between said support arm and said support structure.

References Cited in the file of this patent UNITED STATES PATENTS 

